Wireless telecommunications systems sometimes are divided into a series of cell areas covering a service area. Each cell area has a transmitting base station using an operating frequency set comprising a plurality of radio channels to communicate with mobile subscribers. Each channel represents an information signal at a particular frequency carrier or band.
In many instances it is advantageous to combine these channels for transmission purposes. The channels can all be combined by a broadband signal combiner into a multichannel signal at low power levels and then amplified by a single linear amplifier (or its equivalent, a plurality of linear amplifiers in parallel, each amplifying a reduced power version of the same multi-channel signal) to raise the multi-channel signal to an appropriate transmit power level.
Peak to average ratio compression is a technique of improving average power levels from a transmitter with limited peak power capability. Traditionally, this has been accomplished with adaptive gain control and clipping. These techniques create frequency domain splatter and increase the noise floor of the transmitted signal. In addition, such techniques are not very useful for amplitude modulated signals, which require a high degree of linearity. Thus, a need exists for a method and apparatus for power control in a transmitter that can maintain linear transmitter operation while increasing the average power output of the transmitter.